Amino acid dependent glucose accumulation, previously demonstrated only in Fusobacterium nucleatum (10953), was examined in representative species of fusobacteria. An absolute amino acid energy requirement for glucose accumulation by anaerobically maintained washed cells was demonstrated for most of the species tested except F. necrophorum and F. mortiferum. F. mortiferum accumulated glucose without an amino acid addition, however, almost twice the glucose was accumulated when serine was included; while F. necrophorum accumulated a much smaller fraction of the glucose without an amino acid. F. mortiferum grew well with a wide variety of sugars added to a complex peptone medium in contrast to the other fusobacteria tested. F. mortiferum accumulated glucose, fructose, galactose, mannose, sucrose and maltose and accumulated the sugar best on which it had been grown. Glucose use was constitutive with the sugar accumulated actively be serine grown cells while only maltose grown F. mortiferum would accumulate maltose. The differences in accumulation of the sugars probably reflects the induction of individual sugar permeases because the organism has a common fermentation path and separate kinases have been demonstrated. F. mortiferum accumulates a glycogen like storage material as demonstrated in electron micrographs of thin sections of the organism. The intensity of the granular storage product observed was dependent on the sugar used for growth: galactose, the most and fructose the least. Constitutive kinase activities were demonstrated for glucose, fructose, and mannose in cell extracts from serine or sugar grown F. mortiferum. Purification of the kinase activity revealed a separable glucokinase from a fructokinase which would also phosphorylate mannose. The molecular weight, amino acid sequence, and metal ion requirements of a highly purified F. mortiferum fructokinase revealed that the protein was very similar to a fructokinase isolated by other members of this laboratory from Lactococcus lactis.